Tested on 2013-12-18 using latest nightly. If you have a Nightly build open and you right click on the taskbar icon and select any of the jumplist options, you get an error message saying "Firefox is already running, but not responding..." Steps: 1. Install the nightly on Win8.1 and launch it 2. Right click on the Nightly taskbar icon 3. Select the task "Open New Window" Expected: A new Nightly window opens Actual: You get the "Firefox is already running, but not responding..." error. It also looks like clicking on other apps, for example the News app, in Windows Metro tries to open the Nightly and the same error is displayed.
I have not tried in Win7 yet or WinXP.
2 thoughts: - Maybe when Metro was open you got it. - Maybe you have a different profile that you started with than the default profile?
You need to log in before you can comment on or make changes to this bug.